Check if menu bar buttons are display and functionality works (#2621)

Test the main page for existence of
- theme button visible
  - clicking shows the list of themes
- search button visible
  - and tests successful search for "Welcome"
- language button visible
  - clicking shows the list of languages

this is testing functionality missing in dev environments in
#2588 and is relevant
for #2620

tests/src/generic_page.ts

@@ -0,0 +1,32 @@
+import { describe, it } from "mocha";
+import { expect, browser, $ } from "@wdio/globals";
+
+describe("Generic page", () => {
+  beforeEach(async () => {
+    await browser.url("/");
+  });
+
+  it("should have the default_theme light", async () => {
+    expect(await browser.execute(() => window.default_theme)).toBe("light");
+  });
+
+  it("should have theme button and show theme list on click", async () => {
+    await expect($("#theme-toggle")).toBeDisplayed();
+    await $("#theme-toggle").click();
+    await expect($("#theme-list")).toBeDisplayed();
+  });
+
+  it("should have search button and successfully provide search results on search", async () => {
+    await expect($("#search-toggle")).toBeDisplayed();
+    await $("#search-toggle").click();
+    await browser.keys(["Welcome"]);
+    // any of the <a> links in the searchresults is containing "Welcome"
+    await expect($("#searchresults").$("*=Welcome")).toBeDisplayed();
+  });
+
+  it("should have language button and show language list on click", async () => {
+    await expect($("#language-toggle")).toBeDisplayed();
+    await $("#language-toggle").click();
+    await expect($("#language-list")).toBeDisplayed();
+  });
+});